JPS6324733A - Error resending system - Google Patents

Abstract

PURPOSE:To enable a line having large transmission delay to be utilized, by storing the number of a frame in which an error is detected, issuing a resending request at every block, and setting only the data of the frame in which the error is detected at the previous time out of resent blocks, as valid. CONSTITUTION:The prescribed number of frames 1-4 are blocked and transmitted, and error detection is performed at every frame in transmitted block, and the number of the frame in which the error is detected, is stored in a frame number memory 17, and the resending request by a tone signal generating part 15 is performed at every block, and the data of the frame in which the error is detected at the previous time out of resent one block, is received as valid. Since the resending request is performed for each block, it is possible to permit large allowable transmission delay without increasing the number of data per frame. Furthermore, since the frame in which the error is detected at the previous time out of resent blocks, is received as valid, it is possible to reduce a repeated error at a resending time.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an error retransmission method that can prevent transmission errors when transmitting image information using a facsimile machine or the like.

(b) One-stroke information in conventional technology facsimile machines? It is now possible to convert the signal into a digital signal and transmit it via a telephone line. However, when transmission is carried out via a telephone line, there is a drawback that various noises are mixed in and transmission errors are likely to occur.Therefore, conventionally, the transmitting side performs data framing, and the receiving side performs frame-by-frame error detection. When an error is detected, a retransmission request signal is sent back and the erroneous t frame? An error retransmission method is used to retransmit the error retransmission method.
A tone signal with a specific frequency is used as a retransmission request signal, and the transmitting side detects the return ft of this tone signal and determines that there is an error in the frame before the frame currently being transmitted, and sends an error to the frame currently being transmitted. A system is known in which the previous seven frames are then transmitted again. In this case, the prerequisite is that the tone signal is detected before the transmission of the next 7 frames after the frame in which the error was detected is completed, so the allowable transmission delay is i & [! It is determined.

Therefore, when considering the use of a line with a large transmission delay, such as a satellite line, it is necessary to increase the number of data in one frame to lengthen the time required for transmission. However, there is a problem that as the number of data per frame increases, the error rate increases and the transmission efficiency decreases.

As a method to solve this problem, for example,
A method similarly shown in Japanese Patent No. 4104 is known. This method is affected by transmission delay! In order to eliminate &, a signal indicating the number of the frame containing the error is sent back as a retransmission request signal. In other words, a retransmission request signal? Since it is possible to determine which frame has an error at the time of detection, it is not affected by transmission delay. However, the sending side requires a large memory to store a large amount of transmitted data, and also sends back a 7-rem number.

A modem 91 is installed on the sending and receiving sides to receive the SRL.
There is a problem that the configuration becomes complicated, such as requiring two terminals.

(/C) The problem that the invention seeks to solve.
The present invention provides an error retransmission system that uses a tone signal return system with a simple configuration, can support lines with large transmission delays, and can further reduce the occurrence of re-errors during retransmission.

(2) Means for Solving the Problems The present invention transmits blocks of a predetermined number of frames,
Error detection is performed on the transmitted fim blocks for each frame, and the error detected (n, *frame number Ji) is memorized, and a retransmission request is made for each block. Only frame data is received as valid.

(E) Function The present invention transmits a predetermined number of frames as blocks as described above, and requests for retransmission are made for each block, so 17 frames of data &'? Tolerable transmission delay without much?
It can be made large. Furthermore, among the retransmitted blocks, only t frames with previous errors are received as valid, so it is possible to reduce re-errors during retransmission.

(F) Embodiments Hereinafter, embodiments of the present invention will be explained using a complete example of a facsimile machine. FIG. 1 shows a schematic configuration of a facsimile machine, including a transmitting section... and a receiving section (21 is a telephone port g!, etc., and communication lines 13, etc.
1 is connected. Transmission unit i11 is reading unit] 4), encoding processing unit (5), control components (611 image information memory (7), error memory (8), modem 1911 line control unit qα, tone signal detection unit (11), etc. It consists of a control unit + gli), a microprocessor, and performs processing according to a predetermined program. The reading section i1H reads the contents of the document with an image sensor such as COD, converts it into a digital signal 1c, and sends it to the encoding processing section +51K. Encoding process! 1511″r,
This digital signal 8 is encoded in a predetermined format to compress the data, and is sequentially stored in the image information memory (71) under the control of the control unit (6).
The coded data stored in the VC is set to a predetermined length, for example, 256
Each byte is read out, and the prescribed framing pattern, frame number, and OR
One frame is divided by adding all the error detection data by O calculation or the like. Also, as shown in the same figure (6), 1 block is 47 frames as the position? Defined 0-picture information memory +71 t
'ff, the modem 19) is capable of storing at least two blocks worth of encoded data.

Profit? The framed data (61) is modulated into a signal that can be transmitted to the communication line (31) and sent to the communication line [3] via the line control unit 11G.The tone signal detection unit (
11) is for detecting a tone signal of a predetermined frequency that is error-detected in the receiving section (2) and returned at t''L7, and the detection signal is sent to the control section fil.Control section 1blt!, this detection signal VcF) and sets the error memory +81 NG? to confirm that there was an error transmission? Remember.

Reception 88 F21 includes line control unit α power, modem α3, control unit (I4゜ tone signal generation unit), one-picture information memory αG, frame number memory αη, decoding processing unit (l comb, recording unit α
It consists of an audience, etc. Here modem α3 sends $1
The signal 8 modulated by the modem (9) of No. 11 is demodulated to its original form and sent to another IaJ (14). [The i3E is configured to perform various processes according to the processing program.The control unit α41 controls the modem α
When receiving data demodulated by J, CR is generated for each frame.
The image information is sequentially stored in the image information memory αω while error detection is performed by performing O calculations and comparing it with error detection data. Frame number memory α7Ih stores the number of the frame in which an error has been detected, and is capable of storing at least four numbers. The decoding processing section α decompresses the encoded data taken out from the one-picture information memory block into the same form as the output of the reading section (4) and sends it to the recording section (19). Then, the recording section (2) prints on the recording paper based on the data from the decoding processing section 0&. The tone signal generator (to) is
A tone signal of a predetermined frequency is output according to the instructions from the control unit α, and this signal is sent to the transmission unit tl+ via the line charge@product α general communication line 131, and is detected by the tone signal detection unit (11). .

The cutout of the invention with the above configuration is converted into a digital signal indicating black and white information in the reading section (4), and is further encoded in the encoding processing section (51), and the image information is stored in the image information memory. (7) The coded data of a predetermined length is taken out from the controlled product (61 is the one-stroke information memo month 7), and the framing pattern, frame number 8j, error detection data by aRC calculation, etc. are In addition, the data of frames 1 to 4 (block 1) are collected and transmitted via the modem (911 line control unit 11α) in the order of frame numbers. , nt shall be transmitted by repeating step 0 day a).The receiving unit (
2) is frames 1 to 4 after the delay time of the communication line (3) has elapsed.
Reception is performed in this order.

Here, suppose an error occurs during transmission of frame (21).

It is assumed that frame 1.3.4 has been normally transmitted f''.When the receiving unit (21) receives frame 1, it proceeds to step (SS) and step (61 step (88), but 7 frames 2 When an error is detected in step (S6), the process proceeds to step (S7) and frame number "2" is received.
” is stored in the frame number memory αη. Next are frames 3 and 4? When received, and in step (S8), a predetermined calculation is performed on the 7th frame number to determine the end of one block.
Proceeding to step (S9), frame number memory (171
Check the contents of the
It is detected that the data has been recorded, and the process proceeds to step (81).In the above step, the data of frames 1 to 4 are stored in the image information memory α(lilVc storage σn).Step (812″)
When the IC advances, the control unit Hf1. )-on signal generator (to)
and sends all tone signals back to the transmitter fi+.

At this point, the transmitter 111 has already started transmitting frame 5 (block 2) as shown in FIG. Assume that a tone signal arrives during frame 6 transmission. When tone signal detection 1111 detects tone signal 8, it sends a detection signal to control section (6).

The controlled product (8) stores an error memory (
8) to record that the tone signal will be returned. After the transmission of frame 6 is completed, it is determined whether or not a tone signal is to be returned based on whether or not the NG bit in the error memo January 8 is set. Since the tone signal was returned, it is determined that there was an error in any frame of the previous block (n), and the process proceeds to step (day 4). In step (S4), the retransmission setting for the previous block 1 is performed, and the NG bit of the error memo January 8) is reset.

Transmission of block 2 is then stopped, and block 1 is retransmitted.

On the other hand, in the receiving section (21), after returning the tone signal,
Only the frame number is read out of the n number of frames that are subsequently sent, and that number is stored in the frame number memory 071 as 5.
Determining whether the number is the same as the one you remember? , step (8
11) and step (S14''rC are performed. That is, all 9 incoming frames with errors in the previous block are detected. After transmitting block l, the transmitting unit (1) returns a tone signal. Frames 5 and 6 are transmitted until all the frames are detected, but in step (sra) and step (E+14), it is not determined to be t frames with an error last time, that is, frame 2.
These days, the data of frames 5 and 6 are not captured properly. Next, block 1 is retransmitted, but only when frame 2 is retransmitted, Stella 7' (st+%, step (S16'X
/c Go forward. Then, the data of the retransmitted frame 2 (full-frame information memory 08) is sequentially accumulated in the same manner as the previous time (1yrVc) and proceeds to steps (sxs) a, et cetera (sxyg).
Cram school step (proceed to 818″, frame number memory α
Delete the number "2" stored in η and proceed to step (S
Return to 18). And retransmitted frame 3. After checking the frame, step (81B)? When the end of the retransmission block is determined based on the calculation result of the frame number, the process returns to step (day 9). When the process proceeds from step (S9) to step (StO) based on the erasure of the error frame number "2", one screen is displayed. The data of block l stored in the information memory aυ is sequentially sent to the decoding processing unit α, and the decoded data is as follows.

The green area α9) is printed on the recording paper. On the other hand, if there is an error in retransmitted n*frame 2, frame number 9r
2J is not erased, so return to step (S-).
At this time, it is again determined that the error 7 frame is likely, and the tone signal is returned again. Tone signal return and post-transmission bias section (1)
And in the receiving section (2), the same processing as described above is performed.

When the retransmitted fi7t block l is received without error, the transmitter (1) performs step (Sl) and step (8).
Re-step (SS) is repeated to transmit block 2 in the order of frame numbers. If there is no error in each of the seven frames, the receiving unit 12) repeats step (SS), step (sg), and step (SS) to receive block 2.

The process proceeds from step (day 8) to step (S1O) via step (S9), and printing of block 2 is performed.

Repeat the above steps to transmit and receive the remaining blocks, step (SS) of transmitter 11) and receiver +21.
In step (811), when the end of all blocks is detected, the process proceeds to the next step.

In the above-mentioned embodiments, the case where one transmits and the other only receives is explained, but the present invention is not limited to this, and can be applied to a case where both transmit and receive.

(G) Effects of the Invention As described above, the present invention transmits seven frames of the Fr constant into blocks, detects errors in each frame of the transmitted block, and stores the frame number in which an error is detected. Then, a retransmission request is made for each block, the previous block is retransmitted in response to the retransmission request, and among the retransmitted blocks, only the data of the n7t frame in which an error was previously detected is received as valid, so the allowable transmission delay is 1 block transmission time, and the amount of data per frame is not increased (it is possible to use a line with a large transmission delay, and it is possible to use a line with a large transmission delay, and also to reduce the amount of data that was correctly received last time among the retransmitted blocks).
Since the data of the received frame is not received, it has great practical effects such as reducing the occurrence of re-errors due to retransmission.

[Brief explanation of the drawing]

Figure 1 shows all major inventions applied 7? , a schematic diagram of a facsimile machine, Figure 2 [a) lb) is a diagram showing the data structure of 1 frame and data ia of 1 block, Figure 3 shows the time-related factors of transmission, and Figure 4 shows the transmitter's data structure. 7 to explain the operation
FIG. 5 is a flowchart for explaining the operation of the receiving section. (1) - Transmitter, ! 21-・Receiving unit, +2 communication line, (4)...reading unit, +51-・encoding processing unit, +81.041-・control unit, 171M-・image information memory, 161・, error memory *191. (+31-
...modem! 101. (121-・Line control unit,
fllll・)-on signal detection section, αQ-)-on signal generation section, aη-・frame number memory, α&-・signal processing section, Q9+-・recording section. Applicant: Sanyo Electric Co., Ltd. and one other person Patent attorney Hisatsugu Nishino (one other person) Figure 2

Claims (1)

[Claims] (1) Transmit a predetermined number of frames into blocks, detect errors in each transmitted block, store the number of the frame in which an error was detected, and make a retransmission request for each block. This error retransmission method is characterized in that the previous block is retransmitted in response to the previous block, and of the retransmitted blocks, only the data of the frame in which an error was detected previously is received as valid.